STRAWBERRY STRENGTH OF MATERIALS 415 from hybridizing it with other species. The Indian strawberry (F. Indica) is from upper India, and is naturalized in the southern states ; it differs so much from the other species that it was formerly placed in a distinct genus (Du- chesnea) ; it has yellow flowers, and is a showy house plant, especially for window baskets, but the fruit is dry and tasteless. Of the cul- tivated American varieties, some are pistillate only, and must be planted near perfect flowered varieties, in order that they may be fertilized and bear fruit. The present tendency of cul- tivators is to discard all unisexual kinds. The great step in their improvement was in the production of "Hovey's seedling," raised by 0. M. Hovey of Cambridge, Mass., over 40 years ago ; it is a nearly pure Virginian, and has not been excelled if equalled in quality ; it is a pistillate, and needs careful cultivation. The next great step was in the production of " Wilson's Albany," or " Wilson " as it is gen- erally called, a most hardy and productive va- riety, with perfect flowers. Besides the above, the leading American varieties are "Agricul- turist," " Seth Boyden," " Charles Downing," "Donner's Prolific," "Kentucky," "Nicanor," and " Monarch of the West." Among the Eu- ropean kinds which succeed here on suitable soils are "Triomphe de Gand," "Jucunda," and " La Constante." The cultivation of the strawberry is now an important branch of horticulture, the fruit being sent to the city markets from great distances, especially by water. In New York city the first supplies come from Georgia and the Carolinas; then Virginia, Maryland, and Delaware send large quantities before the New Jersey season be- gins ; this lasts' three or four weeks, and then the later fruit comes from Connecticut and Massachusetts. The culture requires a well fertilized soil ; the plants are formed by run- ners as already described; they may be set in autumn or spring, but the plants must grow one year in place before they give a crop. 'The method of planting and cultiva- tion varies. In the annual method, the plants are set in rows two feet apart and a foot apart in the rows; one crop is taken and the plants are ploughed under, another field being ready to come into bearing to take its place. Another method is to plant in the same manner, let the plants run, and the next spring, when the spaces or paths between the rows are filled with new plants, to plough out other Eaths, turning under the old plants and allow- ig the new ones to bear fruit ; if the alternate spaces are well manured, this method may be continued indefinitely. Still another plan is to cut off all runners as they start, and induce the plants to form large clumps or stools ; some varieties do better in this manner than others ; it is the best plan for gardens, as the plants continue in bearing three or four years. In northern localities the ground is covered with straw or leaves to prevent injury by fre- quent freezing and thawing, and this is left on 767 VOL. xv. 27 until the fruit is picked, to keep it from being soiled. New varieties are produced from seed, from flowers carefully cross-fertilized or not, sown as soon as ripe ; the seedlings come up in four or six weeks, and if protected during the winter and transplanted the next spring, they will bear fruit the following year. STRAYS. See ESTEAYS. STREET, Alfred Billings, an American poet, born in Poughkeepsie, N. Y., Dec. 18, 1811. A lawyer by profession, in 1839 he settled in Albany, where for a .number of years he was state librarian. He has published " The Burn- ing of Schenectady, and other Poems" (1842); "Drawings and Tintings," poems (1844); col- lected poems (1846); "Frontenac," his longest poem (1849) ; " The Council of Revision," con- taining the vetoes of the council, a history of the courts of New York, and biographical sketches of governors and judges from 1777 to 1821 (8vo, 1860); "Woods and Waters, or the Saranacs and Racket," a description of a tour in the great northern wilderness of New York (1860) ; " Forest Pictures in the Adirondacks " (1864); and "The Indian Pass" (1869). STRELITZ. See MECKLENBURG. STRENGTH OF MATERIALS, the resistance of- fered by the materials of construction to change of form or to fracture. 1. The resistance of materials to external forces tending to over- come their cohesion is classified, according to their forms, as follows : T -i A- i I CompressiDg, resisting pulling asunder. Longitudinal, -j Tens ^ res ting crus f ng . I Bending, resisting cross breaking. Transverse < Shearing, resisting cutting across. ( Torsional, resisting twisting or wrenching. Two or more of these forms of resistance are sometimes called into action simultaneously, as in the case of the crank of a steam engine, which tends to break the shaft both by a transverse strain and by torsion. 2. The " ul- timate strength " is the maximum resistance offered to rupture. The " proof strength " is a less degree of resistance, which the body may safely offer when tested. The " working load " is some fractional part of the ultimate strength which may be selected as giving per- fect safety against anticipated strains for an indefinite period. 3. The "factor of safety" is the ratio of the ultimate strength to the working load. The following are minimum values of this quantity adopted in what is gen- erally considered good practice, under " dead " and " live " loads, and where the latter are lia- ble to be accompanied by heavy shocks : MATERIAL. Dead load. Live load. Shock. Wrought iron Steel 8 3 4 4 6 5 6 8 8 10 8 8 10 10 Timber . Masonry 4. The proof strength is usually, and should be always, below the elastic limit, *. e., the point at
